I get a lot of work creating BI/KPI UIs which are basically converting what you can do in Excel Charts into a Web UI.   Which means anything they can do in Excel they expect the web to do. 
Since there is a drive to automate as much mundane human activity in the business and reduce human error (cut and paste error). 
I need to reproduce a graph with 'standard' Tend Lines. 
That is not my interpretation of a trend, but standard best practice.
I want this as a checkbox, and attribute to a series for the DataFieldY value.
Initially a code solution would be fine (once its got the data from the data source).

http://www.telerik.com/blogs/how-to-plot-a-simple-linear-regression-in-telerik-asp.net-web-form-chart